Field of the Invention
The present invention generally relates to an image processing apparatus and an image processing method, particularly to control of the gloss of an image to be generated.
Description of the Related Art
When dye ink using a dye which easily dissolves in water as a coloring material is used in image generation, the coloring material in a solvent permeates fibers of a print medium, so the surface shape of the print medium is maintained even after image generation, and the gloss of the print medium itself is maintained as the gloss of a printed image. However, dye molecules easily decompose with light, and a printed image using dye ink easily fades. Also, when a printed material using dye ink is wet with water, dye molecules having permeated fibers dissolve in water, so a printed image is blurred.
To solve these problems of dye ink, pigment ink using a pigment as a coloring material is recently used in image generation. Unlike a dye which exists in the form of molecules in a solvent, a pigment exists in the form of particles having a size of a few ten nm to a few μm, so a printed material having a high weather resistance is obtained when using pigment ink. A pigment hardly permeates a print medium, but adheres to the surface of a print medium, and forms unevenness on the surface of a printed image, so the gloss of a printed material using pigment ink differs from that of a print medium itself. In addition, due to the characteristics of a resin used in pigment ink and a pigment itself, the surface reflectance of a printed image using pigment ink is higher than that of a printed image using dye ink.
Also, a technique of obtaining a decorating effect by using a gloss difference in a printed material has been developed. For example, Japanese Patent Laid-Open No. 2002-331708 has disclosed an invention of obtaining a decorating effect by changing gloss from one region to another or from one object to another. Recently, a technique of obtaining a decorating effect by using a gloss difference even in a printed material using a pigment ink has been developed.
This technique disclosed in Japanese Patent Laid-Open No. 2002-331708 obtains a desired gloss by determining the use amount of transparent toner as a gloss material based on image clarity set for each object. However, the gloss control range is limited to a range controllable by only the use amount of the gloss material. For example, gloss cannot be controlled at all in a region using no gloss material.
Furthermore, as a technique of controlling gloss although the purpose is not to obtain a decorating effect, Japanese Patent Laid-Open No. 2010-284951 has disclosed an invention which prints ink in the same position in a high-brightness region having a relatively high gloss, thereby increasing the surface unevenness of a printed image and decreasing the gloss. Unfortunately, this method cannot perform control such as an increase in the gloss of a low-brightness region in which the gloss tends to relatively decrease.
As described above, even when obtaining a decorating effect by using a gloss difference in a printed material using pigment ink, no sufficient decorating effect can be obtained because the gloss control range is limited.